You are now entering the PC Anatomy portal

A LUN, or Logical Unit Number, is a unique identifier for a logical disk volume on a storage system like a Storage Area Network (SAN). It is a way to present storage to a host server, allowing it to be accessed and managed as a single drive, even if it's made up of multiple physical drives, partitions, or parts of a RAID group. This enables administrators to allocate, manage, and expand storage capacity efficiently.

Key functions and characteristics

Identification: A LUN provides an address or label so the operating system can identify a specific volume for read/write operations.

Abstraction: It is a logical abstraction layer that sits between the physical storage hardware and the host server, hiding the complexity of the underlying disks.

SAN management: LUNs are a core component of SANs, used to present storage to different servers, control access, and manage capacity.

Flexible presentation: A LUN can be a slice of a larger RAID group, the entire space of a RAID group, or even a combination of multiple drives.

Mountable as a drive: The host server can mount a LUN and assign it a user-friendly drive letter, making it appear as if it's a local drive.

Virtual vs. Physical: A physical LUN maps to a specific, allocated block of storage. A virtual LUN, also called a thin LUN, is a representation of a storage area that can be created in excess of the physical space available, used in technologies like thin provisioning.